Warranties for machines, such as engines, typically become void if it can be shown that the operator of such a machine was negligent in its operation. For example, combustion engines require a minimum level of circulating lubricating oil, or the like, flowing through the engine for the engine to operate at a proper temperature. In the event that the engine is low on oil, the engine components can overheat to the point of causing irreversible damage. Since such an event is the result of neglect on behalf of the operator, and not the fault of engine manufacturers and service personnel who warrant such engines, warrantors would like to prove neglect was the cause of the damage to the engine in such cases. Clearly if neglect can be proven, fraudulent warranty claims can be significantly reduced.
Hastings Co. markets a product called "Heat Tabs" that comprises a disk that is adhered to the engine. The disk includes a heat sensitive material that melts upon reaching a certain critical temperature, such as 250.degree. F., thereby providing visual evidence that the temperature of the engine reached at least 250.degree. F. With such a device installed upon the engine, a person may observe the heat sensitive material to see if it has melted. One drawback to such a device, however, is that it must be adhered to the engine with an adhesive, and is therefore prone to being removed either inadvertently or purposefully. Removal of such a device does not disable the engine. Further, such a device indicates only if the exterior surface of the engine has exceeded the critical temperature. The fluid inside the engine may have reached much higher temperatures. Consequently, in instances where the fluid inside the engine has reached the critical temperature, but the outside surface of the engine has not, such prior art devices will not indicate that the engine temperature reached the critical temperature.
Clearly, then, there is a need for a temperature indicator that indicates if the temperature of fluid within an engine has surpassed a critical temperature. Such a needed device, if removed from the engine, would quickly disable the engine. Further, such a needed device could readily be used in conjunction with a tamper-proof seal that indicates if the device has been removed from the engine. Such a needed invention would not be easily removed from the engine. The present invention fulfills these needs and provides further related advantages.